White lighting on a De Havilland Dash 8 would have blended in with surrounding runway lights, rendering it difficult to see before the aircraft was struck by a landing Airbus A350 at Tokyo Haneda a year ago.

Japanese investigators probing the fatal 2 January 2024 collision have conducted simulations of the A350 pilots’ cockpit view of runway 34R, pointing out that the Dash 8 was aligned with the centreline about 150m beyond the A350’s aiming point.

The simulations, carried out in April and August last year, included depiction of the Dash 8 whose crew was preparing for take-off, having strayed onto the runway unaware of the A350’s approach.

Japan Transport Safety Board says the Dash 8’s position meant its upper and lower tail lights – both white – as well as its white anti-collision strobe would have been visible from behind. But they were all “roughly in the same line” as the 34R centreline lights.

The runway also featured white touchdown zone lighting either side of the centreline in the same area.

JTSB says the Japan Airlines A350 had three pilots in the cockpit: the first officer, who was flying and undergoing A350 route training, the captain who was instructing, plus a safety pilot in the jump-seat who was required under the carrier’s training regulations.

Over the course of the flight both the captain and first officer used their head-up displays, including during the final approach.

The inquiry says the crew was using one of the ‘de-clutter’ modes on the head-up display, to reduce the amount of information presented, adding that the brightness of the symbols can be reduced.

Simulations indicated that the flight path vector on the head-up display was “near the aiming point”, roughly abeam of the precision-approach path indicator lamps, until the aircraft’s flare for touchdown.

The simulation exercises also used eye-tracking to check the pilots’ eye movements, and the inquiry says they showed the crew used conventional cockpit instruments as well as the head-up display.

While the inquiry says the crew did not see the Dash 8 before touchdown – as evidenced by the absence of a go-around attempt – it has yet to draw final conclusions.

But it says a number of factors could have contributed to the pilots’ not being aware of the Dash 8’s presence, other than the blending of its white lights with the runway lighting.

The accident occurred past sunset and twilight, and the moon had not risen, says the inquiry.

It adds that the crew had been cleared to land, and would therefore have expected the runway not to be occupied.

Not only were the pilots engaged in a training scenario, they were also concerned about a possible change in wind direction, and consequently airspeed, during final approach. The inquiry adds that the crew, including the safety pilot, was monitoring air traffic control and heard “no communication that could have raised concerns” about runway 34R being used by other aircraft.